13.3.2Alternate Functions of Port B

The Port B pins with alternate functions are shown in Table 13-6.

The alternate pin configuration is as follows:

• OC0A/OC1C/PCINT7, Bit 7

OC0A, Output Compare Match A output: The PB7 pin can serve as an external output for the Timer/Counter0 Output Compare. The pin has to be configured as an output (DDB7 set “one”) to serve this function. The OC0A pin is also the output pin for the PWM mode timer function.

OC1C, Output Compare Match C output: The PB7 pin can serve as an external output for the Timer/Counter1 Output Compare C. The pin has to be configured as an output (DDB7 set (one)) to serve this function. The OC1C pin is also the output pin for the PWM mode timer function.

PCINT7, Pin Change Interrupt source 7: The PB7 pin can serve as an external interrupt source.

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• OC1B/PCINT6, Bit 6

OC1B, Output Compare Match B output: The PB6 pin can serve as an external output for the Timer/Counter1 Output Compare B. The pin has to be configured as an output (DDB6 set (one)) to serve this function. The OC1B pin is also the output pin for the PWM mode timer function.

PCINT6, Pin Change Interrupt source 6: The PB6 pin can serve as an external interrupt source.

• OC1A/PCINT5, Bit 5

OC1A, Output Compare Match A output: The PB5 pin can serve as an external output for the Timer/Counter1 Output Compare A. The pin has to be configured as an output (DDB5 set (one)) to serve this function. The OC1A pin is also the output pin for the PWM mode timer function.

PCINT5, Pin Change Interrupt source 5: The PB5 pin can serve as an external interrupt source.

• OC2A/PCINT4, Bit 4

OC2A, Output Compare Match output: The PB4 pin can serve as an external output for the Timer/Counter2 Output Compare. The pin has to be configured as an output (DDB4 set (one)) to serve this function. The OC2A pin is also the output pin for the PWM mode timer function.

PCINT4, Pin Change Interrupt source 4: The PB4 pin can serve as an external interrupt source.

• MISO/PCINT3 – Port B, Bit 3

MISO: Master Data input, Slave Data output pin for SPI channel. When the SPI is enabled as a master, this pin is configured as an input regardless of the setting of DDB3. When the SPI is enabled as a slave, the data direction of this pin is controlled by DDB3. When the pin is forced to be an input, the pull-up can still be controlled by the PORTB3 bit.

PCINT3, Pin Change Interrupt source 3: The PB3 pin can serve as an external interrupt source.

• MOSI/PCINT2 – Port B, Bit 2

MOSI: SPI Master Data output, Slave Data input for SPI channel. When the SPI is enabled as a slave, this pin is configured as an input regardless of the setting of DDB2. When the SPI is enabled as a master, the data direction of this pin is controlled by DDB2. When the pin is forced to be an input, the pull-up can still be controlled by the PORTB2 bit.

PCINT2, Pin Change Interrupt source 2: The PB2 pin can serve as an external interrupt source.

• SCK/PCINT1 – Port B, Bit 1

SCK: Master Clock output, Slave Clock input pin for SPI channel. When the SPI is enabled as a slave, this pin is configured as an input regardless of the setting of DDB1. When the SPI0 is enabled as a master, the data direction of this pin is controlled by DDB1. When the pin is forced to be an input, the pull-up can still be controlled by the PORTB1 bit.

PCINT1, Pin Change Interrupt source 1: The PB1 pin can serve as an external interrupt source.

• SS/PCINT0 – Port B, Bit 0

SS: Slave Port Select input. When the SPI is enabled as a slave, this pin is configured as an input regardless of the setting of DDB0. As a slave, the SPI is activated when this pin is driven low. When the SPI is enabled as a master, the data direction of this pin is controlled by DDB0. When the pin is forced to be an input, the pull-up can still be controlled by the PORTB0 bit.

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Table 13-7 and Table 13-8 relate the alternate functions of Port B to the overriding signals shown in Figure 13-5 on page 73. SPI MSTR INPUT and SPI SLAVE OUTPUT constitute the MISO signal, while MOSI is divided into SPI MSTR OUTPUT and SPI SLAVE INPUT.

PCINT0, Pin Change Interrupt source 0: The PB0 pin can serve as an external interrupt source.

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13.3.3Alternate Functions of Port C

The Port C alternate function is as follows:

Table 13-10 and Table 13-11 on page 80 relate the alternate functions of Port C to the overriding signals shown in Figure 13-5 on page 73.

Table 13-10. Overriding Signals for Alternate Functions in PC7:PC4

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